Berlin - Seven luxury cars were set on fire in a rash of attacks early Wednesday in Berlin in what seemed to be a resumption of far-left attacks.

Police have been powerless to stop the intermittent car-burnings, which have occurred for several years now at intervals of a few months in the German capital.

In the first half of last year alone, about 60 expensive cars were burned in a leftist-dominated central district, Kreuzberg. Wednesday's attacks occurred in various areas around Berlin including Kreuzberg, police said.

The preferred modus operandi is to ignite a chemical firelighter of the kind used to start a barbecue fire and place it at a strategic spot under the car. The arsonist has plenty of time to make a relaxed getaway before the flames take hold.

Police suspect some of the attacks down the years were by copycats rather than by the hard-left revolutionaries, who ridicule premium cars as badges of social superiority. Police advise the owners to park such cars in locked garages.

The early Wednesday attacks, over a period of two hours, left 15 cars as write-offs after the flames spread to other parked cars before fire brigades could extinguish each of the fires, according to police.

Three Berlin leftists are currently in custody and on trial over attempted arson attacks in summer 2007 on three army trucks. (dpa)